Tanks in various shapes are used in liquefied gas carriers for marine transportation of a liquefied gas. Among these tanks, there is a case where a horizontal type cylindrical tank is supported by a pair of saddles spaced apart from each other in the axial direction of the tank. Each saddle has an arc-shaped supporting surface extending along the outer peripheral surface of the tank so that even when the ship oscillates (in a case where the axial direction of the tank coincides with the ship length direction, even when the ship rolls), the saddles can receive the load of the tank.
As a horizontal type cylindrical tank, a double-shell tank is known, in which a space between an inner shell storing a liquefied gas and an outer shell encapsulating the inner shell is kept as a vacuum space. For example, Patent Literature 1 discloses a double-shell tank whose outer shell is supported by a pair of saddles, and two support units are disposed between the outer shell and the inner shell over each saddle. That is, four support units are disposed in total.
Over each saddle, the two support units are disposed symmetrically with respect to a vertical line passing through the center of the tank, and each support unit has a structure in which plate-shaped members are stacked in the radial direction of the tank. Specifically, each support unit includes: an outer-shell-side support member disposed on the inner peripheral surface of the outer shell; an inner-shell-side support member disposed on the outer peripheral surface of the inner shell; and a thermal insulating material interposed between these support members.